The invention relates to a plastic package for hydrophilic medical instruments, in particular for hydrophilically coated lancets, which package ensures the hydrophilic nature of the enclosed article over a long period of time.
In medical diagnostics, examination of blood samples or of interstitial fluids permits early and reliable detection of pathological conditions and also specific and reliable monitoring of physical states. Medical diagnostics always entails obtaining a sample of blood or of interstitial fluid from the individual who is to be examined.
To obtain this sample, the skin of the person to be examined can be punctured, for example at the finger pad or ear lobe, with the aid of a sterile, sharp lancet, in order in this way to obtain a few microliters of blood for the analysis. This sampling method is particularly suitable for sample analysis that is carried out directly after the sample has been obtained.
In the area of home monitoring in particular, in other words where persons without specialist medical training carry out simple analyses of blood or of interstitial fluid themselves, and particularly for diabetics taking blood samples on a regular basis, several times a day, to monitor their blood glucose concentration, lancets and associated devices (puncturing aids) are available. These puncturing aids allow samples to be taken with the least possible discomfort and in a reproducible manner, in particular by persons who have no specialist medical training. Lancets and devices of this kind are the subject matter of, for example, WO-A 98/48695, U.S. Pat. No. 4,442,836 or U.S. Pat. No. 5,554,166.
Self-monitoring of blood glucose levels, often carried out at home, is a method of diabetes control that is nowadays applied worldwide. Blood glucose meters in the prior art comprise an analysis device into which a test element (test strip) is inserted. The test element is brought into contact with a droplet of a sample which has been obtained shortly before by means of a puncturing aid, for example from the pad of a finger.
The numerous system components (lancet, puncturing aid, test element and analysis device) require a lot of space and involve quite complex handling. However, systems have in the meantime been developed which have a greater degree of integration and are thus easier to handle and in which, for example, the test elements are stored in the analysis device and made available for measurement. The next step in terms of miniaturization is, for example, the integration of several functions or function elements within a single analytical aid (disposable). The operating sequence can be greatly simplified by suitable combination of the puncturing procedure and of the sensor-based analysis on a test element.
In the prior art, for example, it is known to provide the lancets of such analytical aids with a capillary structure or to make them part of a capillary structure (in this connection see WO 2005/104948 A1). In this case, after the skin has been punctured and the sample emerges, the lancet tip is brought into contact with the sample in order to collect said sample with the aid of the capillary.
The lancet tip for collecting blood or interstitial fluids is typically sterilized in advance and kept in a sterile state by a sterile protector (for example in the form of a cap or pocket) before being used for a puncturing procedure. This ensures that the lancet tip is not contaminated by its surroundings. Moreover, measures are also taken to ensure that, after the skin has been punctured, the lancet tip is shielded (if appropriate by the same cap or pocket), such that accidental injuries and associated infections caused by fluids adhering to the lancet tip are avoided.
In the case of individual lancets, a sterile protector can be produced, for example, by means of the lancet tip being encapsulated with plastic by injection molding in a single operation with the formation of the lancet body. Before use, the user removes this part manually, generally upon insertion of the lancet into the puncturing aid. In the case of lancets stored in a magazine, similar sterile protection devices are customary, for example devices in which the lancet is drawn rearward out of a sterile protector, whereupon the sterile protector is conveyed out of the puncturing path by a spring force. Relatively complicated mechanisms, in particular springs integrated into the equipment, are required for this.
Numerous packages for the medical aids described above have been described in the prior art. EP 1 360 935 A1 describes a tape-like package for a large number of medical aids. The aids are accommodated in depressions in a first tape section that are covered by a second tape section. To ensure the sterile nature of the medical aids, they are sealed by welding in a flexible packaging material.
DE 28 03 345 B1 describes a blood sampling device with a needle that can be moved against the surface of a patient's body by the action of a force. The needles are stored in what are called strip packages, which comprise contiguous pockets. The strip packages are composed of a bottom film and a cover film of paper, plastic sheet or the like, the bottom film and cover film being placed on each other and connected to each other in a ladder-shaped pattern so as to form pockets that enclose the blood lancets on all sides.
WO 2004/075760 A1 relates to an automatically opening package for medical aids that comprises an upper flexible sheet section which has a distal end, a proximal end, a first peripheral edge and a second peripheral edge, and around it a flexible sheet section which has a distal end, a proximal end, a first peripheral edge and a second peripheral edge. The upper and lower flexible sheet sections are designed such that they can be detachably sealed together along at least one segment of their first and second peripheral edges, as a result of which a medical device is enclosed within the upper and lower flexible sheet sections. A collar is mounted on the distal end of the upper flexible sheet section and on the distal end of the lower flexible sheet section, said collar being mounted on the distal ends of the lower and upper flexible sheet sections in such a way that a relative sliding movement of the collar and of the proximal ends of the upper and lower flexible sheet sections that decreases a distance between them causes the upper and lower flexible sheet sections to pull apart. In this way, the package is automatically opened and at least one section of the medical device is exposed.
Moreover, WO 2005/104948 A1 discloses a test magazine with two film tapes which are connected to each other in a sandwich formation and can be wound up and between which there are receiving compartments for test elements, these each comprising a puncturing unit for puncturing body tissue and a test unit to which body fluid is applied.
Lancets and in particular microneedles with capillaries are customarily made of surgical steel, for example a stainless chromium-alloy heat-treated steel with a low carbon content (material number 1.4021), which can pose a problem as regards sampling of blood and interstitial fluids by means of capillary forces. The reason for this lies in the hydrophobic nature of the steel, which at least partially prevents filling of the capillary by means of capillary forces. In order nevertheless to achieve complete or almost complete filling of the capillary, the capillary is usually provided with a hydrophilic coating, in particular with a coating of SiO2, TiO2, polyacrylic acid or dextran sulfate. The hydrophilic surfaces are highly energetic, which has the effect that they gradually reduce their surface energy by absorption of gas molecules onto their surface, and this, in the case of absorption of apolar compounds, leads step by step to a loss of the hydrophilic nature of the coating. The above-described prior art provides no teaching aimed at ensuring the hydrophilic nature of the surfaces of lancets, puncturing aids and medical aids preferably over a long period of time.